Emperor Kōbun (弘文天皇 Kōbun-tennō) was the 39th emperor of Japan, according to the traditional order of succession.

Kōbun's reign lasted only a few months in 671 – 672.

Emperor Kōbun was named the 39th emperor by the Meiji government in 1870; and since the late 19th century, he is known by the posthumous name accorded to him by Meiji scholars.

In his lifetime, he was known as Prince Ōtomo (大友皇子, Ōtomo no ōji). He was the favorite son of Emperor Tenji; and he was also the first to have been accorded the title of Daijō-daijin.

Contemporary historians now place the reign of Emperor Kōbun between the reigns of Emperor Tenji and Emperor Temmu; but the Nihongi, the Gukanshō, and the Jinnō Shōtōki do not recognize this reign. Prince Ōtomo was only given his posthumous title and name in 1870.